Question

Which is the slope of a line that is perpendicular to the line represented by the equation x-y = 8

A. 8
B. 1/8
C. 1
D. -1

Answer 1

Answer:

-1

Step-by-step explanation:   from the equation,  x-y=8,  make  y the subject of the formulae , this gives - y=  -x +8

divide all through by (-) sign, this gives   y= x - 8

from the last equation above, the slope is the coefficient of x which is 1. since it is perpendicula, the answer is -1

by co efficient, we mean the number multiplying the unknown

Answer 2

Answer:

D

Step-by-step explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Rearrange x - y = 8 into this form by subtracting x from both sides

- y = - x + 8 ( multiply through by - 1 )

y = x - 8 ← in slope- intercept form

with slope m = 1

Given a line with slope m then the slope of a line perpendicular to it is

$m_{perpendicular}$ = - $\frac{1}{m}$ = -  $\frac{1}{1}$ = - 1 → D